Explore the vast range of titles available.

Mesomycetozoean-induced infections (order Dermocystida, genus Amphibiocystidium) in European and North American amphibians are causing alarm. To date, the pathogenicity of these parasites in field conditions has been poorly studied, and demographic consequences on amphibian populations have not been explored. In this study, an Amphibiocystidium sp. infection is reported in a natural population of the Italian stream frog (Rana italica) of Central Italy, over a 7-year period from 2008 to 2014. Light and electron microscope examinations, as well as partial 18S rDNA sequence analysis were used to characterize the parasite. Moreover, a capture-mark-recapture study was conducted to assess the frog demographics in response to infection. Negative effects of amphibiocystidiosis on individual survival and population fitness were absent throughout the sampling period, despite the high estimates of disease prevalence. This might have been due to resistance and/or tolerance strategies developed by the frogs in response to the persistence of Amphibiocystidium infection in this system. We hypothesized that in the examined R. italica population, amphibiocystidiosis is an ongoing endemic/epidemic infection. However, ecological and host-specific factors, interacting in a synergistic fashion, might be responsible for variations in the susceptibility to Amphibiocystidium infection of both conspecific populations and heterospecific individuals of R. italica.

Ichthyosporean parasites (order Dermocystida) can cause morbidity and mortality in amphibians, but their ecology and epidemiology remain understudied. We investigated the prevalence, gross and histologic appearance, and molecular phylogeny of a novel dermocystid in the state-endangered silvery salamander ( Ambystoma platineum ) and the co-occurring, non-threatened small-mouthed salamander ( Ambystoma texanum ) from Illinois. Silvery salamanders ( N = 610) were sampled at six ephemeral wetlands from 2016 to 2018. Beginning in 2017, 1–3 m m raised, white skin nodules were identified in 24 silvery salamanders and two small-mouthed salamanders from five wetlands (prevalence = 0–11.1%). Skin biopsy histology ( N = 4) was consistent with dermocystid sporangia, and necropsies ( N = 3) identified infrequent hepatic sporangia. Parasitic 18S rRNA sequences ( N = 5) from both salamander species were identical, and phylogenetic analysis revealed a close relationship to Dermotheca viridescens . Dermocystids were not identified in museum specimens from the same wetlands ( N = 125) dating back to 1973. This is the first report of Dermotheca sp. affecting caudates in the Midwestern United States. Future research is needed to determine the effects of this pathogen on individual and population health, and to assess whether this organism poses a threat to the conservation of ambystomatid salamanders.

Outbreaks of cutaneous infectious disease in amphibians are increasingly being attributed to an overlooked group of fungal-like pathogens, the Dermocystids. During the last 10 years on the Isle of Rum, Scotland, palmate newts (Lissotriton helveticus) have been reportedly afflicted by unusual skin lesions. Here we present pathological and molecular findings confirming that the pathogen associated with these lesions is a novel organism of the order Dermocystida, and represents the first formally reported, and potentially lethal, case of amphibian Dermocystid infection in the UK. Whilst the gross pathology and the parasite cyst morphology were synonymous to those described in a study from infected L. helveticus in France, we observed a more extreme clinical outcome on Rum involving severe subcutaneous oedema. Phylogenetic topologies supported synonymy between Dermocystid sequences from Rum and France and as well as their distinction from Amphibiocystidium spp. Phylogenetic analysis also suggested that the amphibian-infecting Dermocystids are not monophyletic. We conclude that the L. helveticus-infecting pathogen represents a single, novel species; Amphibiothecum meredithae.

Background Sphaerothecum destruens is an obligate intracellular fish parasite which has been identified as a serious threat to freshwater fishes. Taxonomically, S. destruens belongs to the order Dermocystida within the class Ichthyosporea (formerly referred to as Mesomycetozoea), which sits at the animal-fungal boundary. Mitochondrial DNA (mtDNA) sequences can be valuable genetic markers for species detection and are increasingly used in environmental DNA (eDNA) based species detection. Furthermore, mtDNA sequences can be used in epidemiological studies by informing detection, strain identification and geographical spread. Methods We amplified the entire mitochondrial (mt) genome of S. destruens in two overlapping long fragments using primers designed based on the cox 1, cob and nad 5 partial sequences. The mt-genome architecture of S. destruens was then compared to close relatives to gain insights into its evolution. Results The complete mt-genome of Sphaerothecum destruens is 23,939 bp in length and consists of 47 genes including 21 protein-coding genes, 2 rRNA, 22 tRNA and two unidentified open reading frames. The mitochondrial genome of S. destruens is intronless and compact with a few intergenic regions and includes genes that are often missing from animal and fungal mt-genomes, such as, the four ribosomal proteins (small subunit rps13 and 14 ; large subunit rpl2 and 16 ), tatC (twin-arginine translocase component C), and ccmC and ccmF (cytochrome c maturation protein ccmC and heme lyase). Conclusions We present the first mt-genome of S. destruens which also represents the first mt-genome for the order Dermocystida. The availability of the mt-genome can assist the detection of S. destruens and closely related parasites in eukaryotic diversity surveys using eDNA and assist epidemiological studies by improving molecular detection and tracking the parasite’s spread. Furthermore, as the only representative of the order Dermocystida, its mt-genome can be used in the study of mitochondrial evolution of the unicellular relatives of animals.

When the enigmatic fish pathogen, the rosette agent, was first found to be closely related to the choanoflagellates, no one anticipated finding a new group of organisms. Subsequently, a new group of microorganisms at the boundary between animals and fungi was reported. Several microbes with similar phylogenetic backgrounds were soon added to the group. Interestingly, these microbes had been considered to be fungi or protists. This novel phylogenetic group has been referred to as the DRIP clade (an acronym of the original members: Dermocystidium , rosette agent, Ichthyophonus , and Psorospermium ), as the class Ichthyosporea, and more recently as the class Mesomycetozoea. Two orders have been described in the mesomycetozoeans: the Dermocystida and the Ichthyophonida. So far, all members in the order Dermocystida have been pathogens either of fish ( Dermocystidium spp. and the rosette agent) or of mammals and birds ( Rhinosporidium seeberi ), and most produce uniflagellated zoospores. Fish pathogens also are found in the order Ichthyophonida, but so are saprotrophic microbes. The Ichthyophonida species do not produce flagellated cells, but many produce amoeba-like cells. This review provides descriptions of the genera that comprise the class Mesomycetozoea and highlights their morphological features, pathogenic roles, and phylogenetic relationships.

Given the worldwide decline of amphibian populations due to emerging infectious diseases, it is imperative that we identify and address the causative agents. Many of the pathogens recently implicated in amphibian mortality and morbidity have been fungal or members of a poorly understood group of fungus-like protists, the mesomycetozoans. One mesomycetozoan, Amphibiocystidium ranae, is known to infect several European amphibian species and was associated with a recent decline of frogs in Italy. Here we present the first report of an Amphibiocystidium sp. in a North American amphibian, the Eastern red-spotted newt (Notophthalmus viridescens), and characterize it as the new species A. viridescens in the order Dermocystida based on morphological, geographical and phylogenetic evidence. We also describe the widespread and seasonal distribution of this parasite in red-spotted newt populations and provide evidence of mortality due to infection.